Continuous web feeding apparatus

ABSTRACT

A MACHINE FOR MAKING SACKS FROM A DOUBLE LAYER WEB OF THERMOPLASTIC SHEET MATERIAL BY HEAT SEALING AND CUTTING IN WHICH THE WEB IS FED WITH CONTINUOUS MOVEMENT THROUGH THE MACHINE BY BEING CLAMPED AT REGULAR AND ADJUSTABLE INTERVALS BETWEEN PAIRS OF DRIVEN CARRIER MEMBERS EXTENDING TRANSVERSELY OF THE WEB AND CONTAINING THE WEB SEALING AND CUTTING MEANS. THE CARRIER MEMBERS ARE MOVED AROUND THROUGH TWO CLOSED GUIDE TRACKS, ONE ON EACH SIDE OF THE WEB TRAVEL PATH, HAVING VERTICALLY DOWNWARDLY EXTENDING LEADING RACK PORTIONS THROUGH WHICH THE PAIRED WEB-ENGAGAGING CARRIER MEMBERS ARE MOVED DOWNWARDLY BY DRIVING BELTS OR CHAINS CLAMPED BETWEEN THE CARRIER PAIRS, AND HAVING VERTICALLY UPWARDLY EXTENDING RETURN TRACK PORTIONS THROUGH WHICH THE CARRIER MEMBERS ARE MOVED UPWARDLY BY MEANS OF DRIVEN LIFTING CHAINS PROVIDED WITH PROJECTING CAMS ENGAGING UNDERNEATH THE CARRIER MEMBERS, THE SPEED OF THE LIFTING CHAINS BEING ADJUSTABLE WITH RESPECT TO THE SPEED OF THE DRIVING BELTS OR CHAINS.

Nov. 7, 1972 D. G. J. Roos CONTINUOUS WEB FEEDING APPARATUS 5 Sheets-Sheet 1 Filed Feb. 16. 1971 m Q a 4 Nov. 7, 1972' D. G. J. R008 3,702,168'

CONTINUOUS WEB FEEDING APPARATUS Filed Feb. 16, 1971 5 Sheets-Sheet 2 l I I l I I I l I l I I l I I I I I l l l I I I I I I I l I I I l 4.

I I I Nov. 7, 1972 D. G. J. ROOS CONTINUOUS WEB FEEDING APPARATUS Filed Feb. 16. 1971 5 Sheets-Sheet 5 Nov. 7, 1972 D. G. J. ROOS CONTINUOUS WEB FEEDING APPARATUS 5 SheetsSheet 4 Filed Feb. 16. 1971 NOV. 7, 1972 005 3,702,168

CONTINUOUS WEB FEEDING APPARATUS Filed Feb. 16. 1971 5 Sheets-Sheet 5 FIG. 5

CONTINUOUS WEB FEEDING APPARATUS Dirk Godfried Johannes Roos, Amsterdam, Netherlands, assignor to Trans-Atlas A.G., Amsterdam, Netherlands Filed Feb. 16, 1971, Ser. No. 115,351 Claims priority, application Netherlands, Feb. 16, 1970, 7002157 Int. Cl. B65h 17/34 U.S. Cl. 226-110 9 Claims ABSTRACT OF THE DISCLOSURE A machine for making sacks from a double layer web of thermoplastic sheet material by heat sealing and cutting in which the web is fed with continuous movement through the machine by being clamped at regular and adjustable intervals between pairs of driven carrier members extending transversely of the web and containing the web sealing and cutting means. The carrier members are moved around through two closed guide tracks, one on each side of the web travel path, having vertically downwardly extending leading track portions through which the paired web-engaging carrier members are moved downwardly by driving belts or chains clamped between the carrier pairs, and having vertically upwardly extending return track portions through which the carrier members are moved upwardly by means of driven lifting chains provided with projecting cams engaging underneath the carrier members, the speed of the lifting chains being adjustable with respect to the speed of the driving belts or chains.

BACKGROUND OF THE INVENTION This invention relates to a machine for operating on a web of sheet material and more in particular to such a machine for making sacks, by heat sealing and cutting, from a double layer web of thermoplastic sheet material, in which the web is fed with continuous movement through the machine. In a sack making machine of this type the Web of sheet material, which is taken off from a supply roll in the form of a flattened sack tube or of a strip of material that has been folded double in longitudinal direction, is sealed and cut through or preforated at regular distances as defined by the desired dimensions of the sacks to be made in order to form the sacks out of the double layer of material.

In my U.S. Pat. 3,300,365 I have disclosed such a machine for operating on a web of sheet material, which is fed with continuous movement along a path through the machine, in which said machine comprises a plurality of carrier members, each having a web engaging surface and extending parallel to one another transversely of the path of travel of the web through the machine, said members being arranged in two groups, one on each side of said path of travel of the web, at least some of said carrier members including means for operating on said web arranged at said web engaging surface; two guide track means, each for guiding the carrier members of one of said groups for movement in a closed path, each track means comprising a leading track portion and a return track portion each having forward and rear ends, the leading portions of said two track means extending parallel to each other on opposite sides of said path of travel of said web and spaced at a distance from each other for enabling two opposed carrier memebrs of different groups when in opposed positions in said two leading track portions to clampingly engage the web between opposed web engaging surfaces; carrier feed means at the forward ends of said leading track portions for simultaneously feeding a carrier member of each group into the respective track portions; carrier return means at the rear ends of said lead- United States Patent "ice ing track portions for returning the carrier members through their associated return track portions to said carrier feed means; and carrier driving means extending longitudinally adjacent said leading track portions for engaging each pair of opposed cooperating carrier members fed into said leading track portions by said feed means to move said carrier members through said track portions from the forward end to the rear ends thereof.

In this known machine the Web travel path extends from the feed side to the discharge side of the machine slantingly upward at a small angle to the horizontal and, correspondingly, the return track portions of the guide tracks extend slantingly downward toward the carrier feed means. At-the end of the leading track portions the carrier members are clampingly engaged by driven carrier return wheels having a resilient surface which move the carrier members from the leading guide track portions to the return track portions whereupon the carrier members move by gravity through these return track portions to the carrier feed means at the end thereof. Because of this form and design of the known machine it has a great length in the horizontal direction and occupies a large amount of floor space. The carrier members, sliding freely downward through the return track portions, are at the end of their sliding movement intercepting by the preceding carrier members that are waiting for admittance into the feed means whereby the machine is periodically subjected to shocks as a downwardly sliding carrier member hits a preceding stationary carrier member waiting in front of the feed means. Another disadvantage of this arrangement is that the travelling time of the carrier members through the downwardly inclined return track portions is virtually constant at all times irrespective of the adjustable time cycle in which the carrier members are introduced into the leading track portions by the feed means. As a consequence, it is necessary that a sufiicient supply of carrier members should always be available at the feed means so as to ensure that also at a high speed of the feed means, a sufficient number of carrier members is at all times available for engagement by this feed means. As a result, the ratio of the number of carrier members that are operative at a given movement to the total number of carrier members in the machine is unfavourable. The almost horizontal arrangement of the known machine furthermore hampers an easy introduction of a new web of sheet material into the machine whereby in particular the replacement of a used supply roll of material by a full supply roll is time-consuming and a cause of production losses.

SUMMARY OF THE INVENTION The invention has for its object to provide a machine of the kind referred to hereinabove which obviates the above-discussed drawbacks of the known machine.

More in particular, it is an object of the invention to provide a machine of the kind referred to which occupies a relatively small amount of floor space and facilitates the introduction of a new web of material into the machine for treatment.

Another object of the invention is to provide a machine of the kind referred to which in its operation needs only a limited amount of carrier members and in which no shocks occur in the return movement of these carrier members.

The present invention consists, therefore, in a machine for operating on a web of sheet material of the kind referred to hereinabove, in which said leading and return track portions extend substantially in the vertical direction, the carrier members being moved downwardly by said carrier driving means through said leading track portions from the upper front ends to the lower rear ends thereof, and in which said carrier return means comprise for each of said two groups of carrier members a pair of endless lifting means arranged alongside and inwardly of the respective closed guide tracks for movement along these tracks, said lifting means being driven with equal speed in synchronism with said carrier feed means and each being provided with an equal number of equally spaced projecting lifting cam means adapted to engage said carrier members for moving the latter upwardly through said vertical return track portions, each of the two lifting means for a carrier group having for each carrier member of said group a specific associated lifting cam means, and corresponding cam means for all lifting means in their upward movement maintaining at all times a common level whereby the moving lifting means sequentially deliver two opposed carrier members of different carrier groups simultaneously to the carrier feed means at the upper side of said guide tracks.

As a result of this arrangement, the speed at which the carrier members are returned by the lifting means, such as endless chains or belts, through the return track portions to the feed means is at all times adapted to the adjustable speed of this feed means and no additional carrier members are required for forming a buffer supply of carrier members at the inlet side of the feed means. Each of the carrier members conveyed by the lifting means to the feed means on reaching the latter is immediately taken over by the feed means running in synchronism with the lifting means whereby shocks are avoided. Because of the vertical arrangement of the guide tracks, the machine requires relatively little floor space. a

This arrangement further allows to introduce a new web of material to be treated into the machine at the upper side thereof by moving the leading web and vertically downwardly until this web end is gripped by the paired carrier members. The machine may be provided at each of its sides with a support for a supply roll of web material whereby during the treatment of a previously intro duced web a next supply roll may be placed in the machine and be prepared for its feeding into the machine. In this way the change-over from one supply roll to the next can be accomplished with a minimum loss of time.

The distance between two successive pairs of carrier members engaging the carrier driving means, i.e. the sack length l, is defined by the formula:

in which v is the speed of the carrier driving means, v the linear speed of the lifting means and the carrier feed means, and d the distance between successive lifting cams on the lifting means. Since the lifting means cannot run faster along the leading guide track portions than the carrier driving means, it follows from this formula that the smallest possible sack length l is equal to the cam distance d, i.e. when v is equal to \v,,,. If the machine is to be adjusted to a selected greater sack length, the speed v of the carrier driving means must be increased with respect to the speed v of the lifting means which incurs that in the leading guide track portions the carrier mem bers will gradually move away from their associated lifting cams. Depending on the length of these leading track portions, there is thus the danger that when adjusting the machine to making sacks of great length, a pair of carrier members overtakes and strikes against the lifting cams associated with the preceding pair of carrier members. To prevent this and to increase the control range of the sack length, according to a preferred embodiment the lifting cams of the lifting means are alternately arranged in a first and a second of two different lateral positions, the carrier members being provided with projecting carrier cams for co-operation with the lifting earns, the carrier cams of successive carrier members being likewise alternately arranged in two different lateral positions for engagement with the lifting cams in said first and second lifting cam position, respectively, whereby the carrier cams of a carrier member can overtake and pass the lifting cams associated with the preceding carrier member. A sufliciently Wide control range for the sack length is thus obtained.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be further described by way of example, with reference to a preferred embodiment of the machine shown by the accompanying drawings in which:

FIG. 1 is a vertical section of the machine according to the invention, taken along the plane I-I of FIG. 2 as seen in the direction of the arrows;

FIG. 2 is also a vertical section of the machine taken along the plane IIII of FIG. 1, i.e. perpendicular to the sectional plane of FIG. 1;

FIG. 3 is a horizontal section taken along the plane III-III of FIG. 2;

FIG. 4 is a top view of part of the machine; and

FIG. 5 is a horizontal section taken along the line VV of FIG. 1 and showing a variant of the driving means of the feed rolls.

DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION The machine as shown in the drawings has a frame with two vertical parallel side plates 1 and 2 each of which is mounted on a beam frame 3', which two frames are connected on the lower side and on the upper side by transverse beams 4. A double layer web 5 of material to be processed, such as a sack tube of thermoplastic material, is fed downwardly through the machine along a linear vertical web travel path 6 in a manner yet to be described.

On the inner side of each side plate 1 and 2, two closed guide tracks 7, 8 and 9, 10, respectively, are arranged consisting of U-shaped rails secured to these side plates. The guide tracks all have the same shape and are oppositely and symmetrically arranged on either side of the vertical web travel path 6, the guide tracks 7 and 9 being positioned on one side of this web travel path and the guide tracks 8 and 10 being positioned on the other side thereof. Each guide track has on the side facing the web travel path 6 a leading guide track portion 11, 11, respectively, extending parallel to the web travel path; a return guide track portion 12, 12' (FIG. 2), respectively, arranged at some distance to the left and to the right thereof, respectively, and likewise parallel to the web travel path 6; a semicircular lead-in bend portion 13, 13', respectively, connecting these two guide track portions at the upper side, and a semicircular lead-back bend portion 14, 14, respectively, connecting these parallel track portions at the lower side. Each pair of opposite guide tracks 7, 9 and 8, 10 serves for guiding carrier members 15, of which only a few are shown in FIG. 1. The carrier members have an elongate shape and extend parallel to the plane of the Web travel path and perpendicularly to the direction of motion of the web. The carrier members 15 are provided at each end with two shaft journals arranged side by side and extending in the longitudinal direction of carrier member, these shaft journals bearing two travelling rollers 16 that run in the corresponding guide track channels. The ends of the carrier members furthermore are each provided, on the outside of these traveling rollers, with a guide roller 17 the axis of which is perpendicular to that of the travelling rollers 16 and which run along the channel bottom of the corresponding guide track. This way of supporting the carrier members with rollers 16 and 17 in the opposite guide track channels allows the carrier members when moving through the guide tracks to maintain their proper transverse and longitudinal position parallel to each other and to the web travel path 6, and also prevents them from rotating about their longitudinal axes with respect to the guide tracks.

Each of the two guide track circuits on either side of the web travel path 6 comprises an equal number of carrier members; there are six in the embodiment shown in the drawings. With the aid of the feed mechanism described hereinafter, a carrier member of the one and a carrier member of the other guide track circuit are in each instance fed simultaneously through the lead-in bend portions 13 and 13 into the leading guide track portions 11 and 11. These leading guide track portions 11 and 11' are arranged at such a short distance from each other that the opposite carrier members of such a pair of carrier members while moving through these track portions are enabled to clampingly engage the web of material between their facing outer surfaces, thus carrying along the web in their movement. To this end, the carrier members 15, on their sides which face outwardly, are provided with strips 18 of a somewhat resilient material such as silicone rubber, which strips extend over the greater part of the length of the carrier members (FIG. 3). The carrier members furthermore comprise, in these outwardly facing sides, means for treating the web of material, such as, for example, means for transverse heat sealing and cutting or perforating the double web of material or sack tube, so as to form the individual sacks therefrom. Embodiments of such treating means are described in my abovementioned US. Pat. 3,300,365 and will be briefly discussed hereinafter.

The carrier members 15 are driven through the leading guide track portions 11, 11' by two endless drive chains 19, the links of which bear rubber blocks and which on one side of the machine pass around two chain wheels 21 fastened on a driven shaft 20, and on the other side of the machine pass round chain guide pulleys 23 mounted on two separate short spindles 22. The two drive chains are arranged closely adjacent the side plates 1 and 2 and their vertically downwardly moving leading portions are situated in the plane of the web travel path on either side thereof. The carrier members 15 have at each of their ends a recessed portion in which a clamp plate 24 is fitted and the opposite clamp plates 24 of two co-operating carrier members 15 moving through the leading guide track portions 11, 11 are at a distance from each other allowing them to clampingly engage the chain 19 which is situated between them (FIG. 3). As a result, the successive pairs of carrier members are moved from above downwardly through the leading guide track portions 11, 11 by the drive chains 19. Instead of chains, also endless rubber belts may be used to which the paired carrier members can attach themselves.

When the carrier members have reached the end of the leading track portions 11, 11' they are again fed in pairs by a return mechanism and a feed mechanism to the top entrance end of these track portions.

The return mechanism comprises two coupled, continuously driven shafts 25 and 26 which rotate in opposite direction as indicated by the arrows, but at the same speed. The shafts 25 and 26 are so supported in the side plates 1 and 2 that their axes pass through the centres of the semicircular lead-in bend portions 13, 13 of the guide tracks. The shaft 25 bears two chain wheels 27, and the shaft 26 two chain wheels 27 two lifting chains 28 run over the two chain wheels 27, and two lifting chains 28 over the chain wheels 27'. On the lower side, these four chains pass over chain wheels 29, 29' of the same diameter as the chain wheels 27, 27 and rotating freely on two shafts 30, 30 likewise supported in the side plates 1 and 2 and the axes of which pass through the centres of the semicircular lead-off bend portions 14, 14 of the guide tracks.

The lifting chains lie in vertical planes inwards from and in close proximity to the drive chains 19, the diameter of the chain wheels 27, 27' and 29, 29 being so selected that the lifting chains run on the inside of the closed guide track circuits and parallel to the leading and return track portions thereof.

Each of the lifting chains 28, 28' bears six lifting earns 32 and 33 which are evenly spaced over the chain length and project to the one and to the other side, respectively, transversely to the plane of the chain. Furthermore, each carrier member is equipped on its side facing the lifting chains with two L-shaped carrier cams 34 or 35, adapted to co-operate with the lifting cams 32 and 33, respectively, three of the carrier members thus having cams 34 laterally inwardly of the lifting chains and adapted to be engaged by the chain lifting earns 32 and the intermediate other three carrier members having carrier cams 35, laterally outwardly of the lifting chains and adapted to be engaged by the lifting cams 33. Each carrier member has a particular pair of lifting cams, one on each of the two lifting chains, associated therewith which pair of lifting cams, during the travel of the associated carrier member through the return guide track portions 12, 12', engage underneath the two carrier earns 34, 35 of the carrier member to support the latter in a horizontal position. Furthermore, the pairs of lifting cams of the lifting chains 28 and 28 on either side of the web travel path and associated with a co-operating pair of carrier members supported the two carrier members during the return travel consistently on the same level, so as to deliver these two members simultaneously to the feed mechanism.

This feed mechanism comprises forked catch members 36, two of which are fitted on each of the driven feed shafts 25 and 26 and which can engage virtually without play about rollers 36a provided on the rear faces of the carrier members (FIG. 3). The diameter of the chain wheels 27, 27' is so selected that the length of the wheel circumference is equal to the distance between the cams of the lifting chains, so that a next pair of carrier members is fed by the lifting chains upon each completed revolution of the shafts 25 and 26. The catch forks 36 are secured on these shafts 25, 26 in such angular positions that they successively engage each pair of carrier members arriving at the feed mechanism, take it over from the lifting cams concerned, pass it through the lead-in bend portions 13, 13 of the guide tracks, and deliver the paired carrier members directly opposite each other into the leading guide track portions 11, 11. As an additional measure to ensure the proper relative position of the two co-operating carrier members 15 of a pair of carriers, the carrier members of the one guide track are provided on their outwardly facing side with two pins 37 having conical ends (FIG. 3) which mate with corresponding sockets 38 of the carrier members in the other guide track, in which manner the carrier members of each pair are exactly centered with respect to each other during the travel through the leading guide track portions.

The distance between two successive pairs of carriers clamped onto the drive chains 19 and clampingly engaging the web of material 5 between them in the leading guide track portions 11, 11 is a function of the ratio of the speed of the drive chains 19 to the speed of the lifting chains 28, 28 which determines the feed of carrier members. The smallest possible distance between the pairs of carrier members, i.e. the smallest possible sack length, occurs when the drive chains 19 move at the same speed as the lifting chains 28, 28 in which case the carrier members do not become detached from the lifting earns 32, 33 during their travel through the leading guide track portions. The machine can be adjusted to a greater distance between the pairs of carrier members, i.e. to a greater sack length, by selecting a higher speed for the drive chains than for the lifting chains. In such case, the pairs of carrier members that are travelling in the leading guide track portions run away from their associated lifting cams, as indicated in FIG. 2. The alternate disposition of the lifting cams 32, 33 and the carrier member earns 34, 35 on the one and on the other lateral side of the lifting chains, as described hereinabove, makes it possible for a pair of carrier members, in the course of its travel through the leading guide track portions, to pass the lifting cams belonging to the pair of carrier members which travel ahead of it. This results in a wider control range and in a maximum sack length equal to about twice the distance between the lifting cams, which is generally amply sufiicient. If desired, however, still greater sack lengths can be obtained by removing from each guide track three carrier members with identically positioned carrier cams, or four or even five carrier members can be thus removed.

The return mechanism comprises, in addition to the lifting chains 28, 28, rubber-lined outlet wheels 39, 39,

two of which are fixedly secured on the shaft 30 and two on the shaft 30' at the lower side of the guide tracks. The radius of the wheels 39, 39 is such that they engage the rear side of the carrier members with a light Clamping action when these members reach the lead-off bend portions 14, 14'. The shafts 30, carrying the wheels 39, 39' are rotatably supported in the side plates 1 and 2 in which, however, a brake mechanism (FIG. 1) applies a friction torque to the shafts.

When a pair of carrier members reaches the lead-off bend portions 13, 13 of the guide tracks, the two carrier members move apart and become disengaged from the drive chains 19, while at the same time releasing the treated web of material 5. Each carrier member is clampingly engaged by the relevant outlet wheels 39, 39' and thus rotates these Wheels and the associated shaft 30 or 30 during its rotational movement through the lead-off bend portion. At the same time, the speed imparted to the carrier member by the drive chains 19 is gradually braked by the brake mechanism 40. Shortly before the carrier member comes to a stop it is overtaken by the associated lifting cams 32 or 33, respectively, of the lifting chains concerned, which cams engage underneath the L-shaped carrier cams on the carrier member and convey the carrier member upwardly through the return guide track portion 12 or 12, respectively, until the carrier member is again engaged by the catch forks 36 of the feed mechanism.

If desired, the shafts 30 and 30' may also be provided with a unidirectional freewheel clutch which prevents these shafts from performing a reverse rotation. Accordingly, should the carrier member come to a stop in the lead-off bend portion before its lifting cams have reached it, it cannot move back downwardly through the bend, but remains stationary at the point that has been reached to wait for the arrival of the lifting cams.

FIGS. 1 and 2 show schematically the means for driving and controlling the machine. An electric motor 41 drives through a clutch 42 (FIG. 1) the input shaft of a variable transmission mechanism 43, the gear ratio of which can be continuously adjusted by turning a control shaft 44. The mechanism 43 can be of any suitable known type. The output shaft of the mechanism 43 drives through a chain wheel 46 secured thereon, a chain 47, idler wheels 48, and a chain 49, a chain wheel 50 mounted on the shaft 25. The shafts 25 and 26 are coupled to each other by two engaging toothed wheels 51 of equal diameter mounted one on each shaft (also see FIG. 4), whereby these shaftsand therefore the lifting chains 28, 28' and the catch forks 36are driven synchronously in the desired directions. On the side turned away from the coupling gears 51, the shaft 26 bears a large toothed wheel 52 which, by way of a set of gear wheels 53 (FIG. 2), drives the input shaft of a second variable transmission mechanism 54, which can likewise be of any suitable known design and the gear ratio of which can be continuously adjusted by means of a hand wheel 55. The output shaft of the mechanism 54 drives through a set of gear wheels 56, a toothed wheel 57 and a variable differential gear 58, the shaft 20, and therefore the driven chains 19.

It follows from the foregoing that by adjusting the hand wheel the speed of the drive chains 19 can be continuously regulated with respect to the speed of the lifting chains 28, 28, thus allowing the distance between the successive pairs of carrier members moved along by the drive chains 19 and therefore the sack dimension in the longitudinal direction of the web 5 to be accurately adjusted within wide limits, as discussed hereinabove. Furthermore, adjustment of the control shaft 44 of the variable transmission mechanism 43 allows the production rate of the machine as a whole to be continuously regulated without changing the ratio of the speed of the drive chains 19 to the speed of the lifting chains 28, 28'. The control shaft 44 is coupled by a pair of conical gears 59 to a horizontal shaft 60 arranged transversely thereto and rotatably supported at the underside of the frame of the machine parallel to the web travel path 6, which shaft 60 bears a hand wheel 61 by means of which the machine speed can be manually adjusted.

The web of material 5 to be processed is fed from the upper side of the machine over a feed cylinder 62, and is guided vertically downwards from this cylinder in the plane of the web travel path 6, where the web is engaged by the paired carrier members in the leading guide track portions 11, 11. To this end, the feed cylinder 62 is mounted on the driven shaft 20 and has the same diameter as the chain wheels 21 which are likewise fitted on this shaft 20, so that the web 5 fed by the cylinder 62 has the same linear speed as the drive chains 19 and the paired carrier members moved along by them. Adjacent the feed cylinder 62, a second similar feed cylinder 63 is mounted on a shaft 64 likewise rotatably supported in the side plates 1 and 2. The web 5 can also be fed over this second feed cylinder 63, as will be discussed hereinafter.

The web of material to be processed can be provided, for instance, in the form of supply rolls manufactured elsewhere, or can be supplied as a continuous web directly by a web extruder means arranged in line with the machine or by some other apparatus for forming or preparing the web of material. The machine illustrated is suitable for both web-supplying methods, and the means therefor are both diagrammatically represented in FIG. 2, although the two possibilities of web supply will, of course, not be used both at the same time.

In supplying the web of material 5 from an extrusion apparatus (not shown), it is important that the production rate of the sack-making machine be automatically adapted to the production rate of the extruder, As indicated in FIG. '2, this is attained by first passing the web 5 coming from the extruder underneath a tensioning roller 65, from where this web travels upwards to the feed cylinder 21. The tensioning roller 65 is rotatably mounted on a shaft secured at its ends to two endless chains 66 arranged closely adjacent the side plates 1 and 2 and each protectively accommodated inside a channel beam 67 secured to the side plate concerned. Each chain 66 runs at the upper side over an idle chain wheel 68 and at the lower side over a chain wheel 69 secured to the control shaft 60. The two chains 66 thus support the tensioning roller 65 horizontally and form a vertical guide for this roller, each vertical displacement of the tensioning roller resulting in a corresponding rotation of the control shaft 60, and thus of the control shaft 44 controlling the machine speed. If, for instance, during the operation of the machine the production rate of the extruder increases, the tensioning roller 65 will move downwardly, causing the control shaft 44 to turn and adjust the transmission mechanism 43 to an increased machine speed. A decrease of the supply rate of the web of material 5 causes the reverse to occur, the transmis sion mechanism 43 then being adjusted to a lower machine speed. In this manner the speed of the machine is automatically and continuously adapted to the supply rate of the web.

For handling webs of material supplied in roll form, the machine is equipped on both sides with laterally projecting supports 70 each adapted to receive a supply roll 71 or 72, the roll shaft 73 or 74, respectively, fitting in recesses provided in the supports (FIG. 2).

Rubber-lined pressure rollers 75 and 76 (shown only in FIG. 2) are arranged to rest on the feed cylinders 62 and 63, respectively, the ends of each pressure roller being rotatably supported in two parallel arms 77 and 78, respectively. These parallel arms extend across the feed cylinders, their inwardly facing ends being pivotably secured to a common spindle 79 and their outwardly facing ends supporting guide rollers 80 and 81, respectively, for the web of material.

In putting the machine into operation, for instance first the supply roll 71 is placed upon the supports 70 on the right side by means of the shaft 73 passed through the core of the roll whereupon the forward end of the web is run over the guide roller 80 and between the feed cylinder 62 and the pressure roller 76 until this forward end portion of the web depends vertically from the feed cylinder 62 closely above the leading track portions 11, 11'. The machine is then started, causing the feed cylinder 62 as well as the drive chains 19 and the lifting chains 28, 28' to be driven in the manner described hereinbefore. The sudden acceleration of the mass of the roll 71 causes the web to be tensioned between the roll and the guide roller 80. As a result, a downwardly directed pressure is applied to the arms 77 whereby the pressure roller is pressed with great force upon the feed cylinder 62 and slip of the web is restricted to a minimum as it passes between the cylinder and the pressure roller. The downwardly moving leading end of the web is engaged between a pair of carrier members and conveyed downwardly through the leading guide track portions 11, 11.

During the operation of the machine, a next supply roll 72 may be placed upon the support 70 on the left hand side and the leading end of the web of this roll can be passed over the guide roller 81, between the stationary feed cylinder 63 and the pressure roller 75 and downwardly over this feed cylinder until the leading end 82 of this web depends just short of the upper end of the leading guide track portions 11, 11.

Accordingly, when the Web of the roll 71 has been used up, a change-over to the web of the roll 72 can be effected immediately by stopping the feed cylinder 62 and driving the hitherto stationary feed cylinder 63. The ends of the shafts and 64 extending through the side plate I carry interengaging toothed coupling wheels 83 of equal size whereby, when the machine is in operation, the coupled shafts 20 and 64 continuously rotate at the same speed but in opposite directions. The feed cylinders 62 and 63 are rotatably but axially non-slidably mounted on the shafts 20 and 64, respectively, and, as schematically shown in FIG. 4, these cylinders can be alternately engaged with and disengaged from the shafts 26 and 64 by means of suitable clutch devices 84. FIG. 5 shows a preferred embodiment of these clutch means allowing automatic change-over from the one to the other feed cylinder. The feed cylinder 62 is mounted for free rotation on the shaft 20 by means of ball bearings 85 and has on its one end a toothed wheel 86 fixedly secured thereon. The feed cylinder 63 likewise rotates freely on the shaft 64 by means of ball bearings 87 and the hub 88 of which cylinder supports, by means of a ball bearing 89, a toothed wheel 90, which is in engagement with the toothed wheel 86 and has the same diameter as the latter. The toothed wheel 90 is coupled to the shaft 64 by means of a remote-controlled electromagnetic clutch 91. At the other end of the feed cylinder 63 a second electromagnetic clutch 92 is arranged by means of which this feed cylinder can be coupled to the shaft 64. Preferably, the clutches 91 and 92 each incorporate a built-in spring-loaded brake which, when the clutch 91 is disengaged, holds the toothed wheel 90 in the stationary clutch housing and which, when the clutch 92 is disengaged, holds the feed cylinder 63 to the stationary clutch housing (not shown in the drawing).

As shown schematically in FIG. 2, the webs from the rolls 71 and 72 each pass between a source of light 93 1G or 94, respectively, and a photoelectric cell 95 or 96, respectively, arranged opposite thereto, which photoelectric cells through suitable electric circuit means of known design (not shown) control the electromagnetic clutches 91 and 92.

As long as the machine operates with the web from the roll 71, the electromagnetic clutch 91 is engaged and the electromagnetic clutch 92 is disengaged. The feed cylinder 62 is rotated by the driven shaft 20, through the toothed wheels 83, the shaft 64, the engaged clutch 91 and the toothed wheels 90, 86, whereas the feed cylinder 63 is held stationary under the action of the spring loaded brake of the disengaged electromagnetic clutch 92. When the material from the roll 71 has been fully consumed and the end of the web thereof has passed the photoelectric cell 95, this cell responds by an output signal which cause the electromagnetic clutch 91 to be disengaged and the electromagnetic clutch 92 to be engaged. As a resuit, the feed cylinder 63 is now rotated by the driven shaft 20 through the toothed wheels 83, the shaft 64 and the clutch 92 whereas following the disengagement of the clutch 91 the feed cylinder 62 is no longer driven but is braked and held by the spring-loaded brake of this latter clutch. The now rotating feed cylinder 63 advances the leading end of the web of the roll 72 and introduces this web end into the machine. While this roll is being used, a new roll can be positioned on the other side of the machine as described hereinbefore, so that, after the roll 72 is finished, the machine can again change-over automatically to the next roll 71 in a similar manner.

As follows from the foregoing, the machine can operate continuously both when the web is supplied from an extruder and when it is supplied from rolls whereby the rate of production is greatly increased.

If a preprinted web of material 5 is to be treated, it is important that the successive operations-such as welding, cutting or perforatingshould each time be performed at identical places with respect to the successive imprints. However, in many cases the mutual distances between the prints show slight deviations, which may be caused, e.g. by a shifting in the printing machine or by a stretch of the web of material. A cumulation of such slight deviations could result in that finally the places of web treatment cross the imprints. This may be prevented by providing printed marks at regular intervals on the web and by arranging a photoelectric cell, such as 97 (FIG. 2), in the path of these marks. The photoelectric cell 97 thus responds to the passage of the printed marks and its output signals may control in a manner as such well known in the art a positioning device 98 (FIG. 1) having an output shaft bearing a chain wheel 99 which by a chain 100 adjusts a chain wheel 101 forming part of the differential gear 58. In this Way, the driven shaft 20, and therefore the drive belts 21, may be moved forwardly or rearwardly through a small angle with respect to the shaft 25, 25 controlling the infeed of the carrier members, according as to whether the printed marks pass the photoelectric cell 63 too late or too early.

' The means for treating the web of material 5 accommodated in the carrier members may take several different forms and embodiments of such treating means are shown and described in the aforementioned US. Pat. 3,300,365. The carrier members 15 constitute channel sections which, when moving through the leading guide track portions 11, 11', face one another with their open sides and which accommodates the above mentioned resilient pressure strips 18. Each carrier member may have two such pressure strips, separated from each other by a longitudinally extending slot, for the purpose of cla-rnpingly engaging the web of material. At least some of these pressure strips have, at their outwardly facing side, embedded therein an electric resistance wire (not shown in the drawing) extending over the full length of the strip which resistance wire receives electric power during the travel of the corresponding carrier member through the leading guide track portions 11, 11' in order to produce a heat seal transversely to the folded web or sack tube. Depending on the thickness of the web, the carrier members of both groups of carrier members, or only the carrier members of one of these groups may comprise such a resistance wire. Also, a resistance wire can be arranged either in only one of the two pressure strips of each carrier member concerned or in both of said strips. In the latter case in each instance two closely adjacent transverse seals are made in the web. Electric power is supplied to the resistance wire by means of a contact brush 102 (FIG. 3) secured to the carrier member 15 and connected to one end of the resistance wire or wires thereof, which contact brush slides along a contact rail 103 when the carrier member travels through the leading guide track portion. This contact rail extends over a given, e.g. adjustable, length along the leading guide track portion and is connected to one pole of a source of electric power. The other end of the resistance wire or Wires is connected to the machine frame as is the other pole of the source of electric power.

FIG. 3 further shows that the carrier members of one of the two groups of carrier members can each be provided with a cutting device for severing the web. This cutting device comprises a carriage 104 mounted for longitudinal movement inside the carrier member and accommodating a knife 105 which projects outwards between the two parallel pressure strips 18 of the carrier member. This carriage is attached to an endless rope 106 running over pulleys 107 secured to shafts which are rotatably mounted adjacent both ends of the carrier member, the ends of these shafts extending through the bottom of the carrier member each bearing a knurled wheel 108 or 109, respectively. As the carrier member travels through the leading guide track portion, the knurled wheel 108 rolls along a rubber strip 110 extending along this guide track portion whereby the knurled wheel is rotated and drives the rope 106. The carriage 104 with the knife 105 is thus pulled by the rope from left to right, as seen in FIG. 3, through the carrier member whereby the knife 105 transversely severs the web of material close to the single seal or between the two parallel seals being made therein, as the case may be. As the carrier member travels through the return guide track portion, the other knurled wheel 109 rolls along a similar rubber strip 111 whereby the carriage is returned to its initial position.

If the web of material should not be cut but perforated, instead of the knife 105 a spring-mounted steel roller may be mounted in the carriage 104, which roller is pressed towards a longitudinally extending perforating cutter member (not shown) of known design mounted lengthwise in the opposite carrier member.

The double layer web 5 can be a sack tube or a sheet which is folded double in the longitudinal direction. The obtained sacks cut from this web are collected, stacked and removed at the lower end of the machine in a manner not further specified.

With the sack making machine as above described it is possible to produce sacks with a very small tolerance of the selected sack length, e.g. a variation of less than half a millimetre in a sack length of two metres. This result is substantially to be attributed to the fact that the carrier feed mechanism delivers the carrier members to the leading guide track portion at a relatively high speed. Furthermore, at the moment the carrier members become disengaged from this feed mechanism and are clampingly engaged on the drive belts, the force of gravity helps to accelerate the carrier members to the speed of the drive belts. Accordingly, when the carrier members are taken over by the drive belts, there is virtually no slip. Another advantage of the machine according to the invention is that the carrier members can be very simply removed from the machine for inspection or other purposes and again be re-inserted into the return track portions of the machine. When the machine is at standstill. a carrier member resting on two lifting cams in the return track portion can be gripped by hand and lifted at one end by a simple turning motion until its guide rollers become disengaged from the guide tracks 7, 9 or 7, 10, respectively. The control range of the sack lengths can thus be increased by simply removing or adding carrier members in the manner as described hereinbefore.

While the invention has been described with reference to a specific embodiment thereof, other embodiments may be resorted to within the scope of the following claims.

What I claim is:

1. A machine for operating on a web of sheet material, which is fed with continuous movement along a path through the machine, said machine comprising a plurality of carrier members, each having a web engaging surface and extending parallel to one another transversely of the path of travel of the web through the machine, said members being arranged in two groups, one on each side of said path of travel of the web, at least some of said carrier members including means for operating on said web arranged at said web engaging surface; two guide track means, each for guiding the carrier members of one of said groups for movement in a closed path, each track means comprising a leading track portion and a return track portion each having forward and rear end, the leading portions of said two tracks means extending parallel to each other on opposite sides of said path of travel of said web and spaced at a distance from each other for enabling two opposed carrier members of different groups when in opposed positions in said two leading track portions to clampingly engage the web between opposed web engaging surfaces; carrier feed means at the forward ends of said leading track portions for simultaneously feeding a carrier member of each group into the respective track portions; carrier return means at the rear ends of said leading track portions for returning the carrier members through their associated return track portions to said carrier feed means; and carrier driving means extending longitudinally adjacent said leading track portions for engaging each pair of opposed cooperating carrier members fed into said leading track portions by said feed means to move said carrier members through said track portions from the forward ends to the rear ends thereof,

in which said leading and return track portions extend substantially in the vertical direction, the carrier members being moved downwardly by said carrier driving means through said leading track portions from the upper front ends to the lower rear ends thereof, and in which said carrier return means comprise for each of said two groups of carrier members a pair of endless lifting means arranged alongside and inwardly of the respective closed guide tracks for movement along these tracks, said lifting means being driven with equal speed in synchronism with said carrier feed means and each being provided with an equal number of equally spaced projecting lifting cam means adapted to engage said carrier members for moving the latter upwardly through said vertical return track portions, each of the two lifting means for a carrier group having for each carrier member of said group a specific associated lifting cam means, and corresponding cam means for all lifting means in their upward movement maintaining at all times a common level whereby the moving lifting means sequentially deliver two opposed carrier members of different carrier groups simultaneously to the carrier feed means at the upper side of said guide tracks.

2. The machine as claimed in claim 1, in which said lifting cams of the lifting means are alternately arranged in a first and a second of two different lateral positions, and in which the carrier members are each provided with projecting carrier cams for co-operation with said lifting cams. the carrier cams of successive carrier members being likewise alternately arranged in two different lateral 13 projections for engagement with the lifting cams in said first and second lifting cam position, respectively, whereby the carrier cams of a carrier member may overtake and pass the lifting cams associated with the preceeding carrier member.

3. The machine as claimed in claim 1, in which each guide track includes a semi-circular lead-in portion joining the upper ends of the return track portion and and leading track portion, and a semi-circular lead-off portion joining the lower ends of the leading track portion and the return track portion, said feed means for the carrier members comprising for each guide track two driven chain wheels mounted for rotation about the axis passing substantially through the centre of curvature of said semicircular lead-in portion concerned and said carrier return means for each guide track likewise comprising two chain wheels mounted for rotation about an axis passing substantially through the centre of curvature of the semicircular lead-oif portion concerned, said two lifting means for each carrier group including two endless chains, each passing over one of said chain wheels at the lead-in track portion and the lead-off track portion whereby said lift ing chains between these chain wheels extend parallel to and inwardly of the leading track portion and return track portion, respectively of the guide track concerned.

4. The machine according to claim 3 in which said feed means for each carrier group comprises at least one forked catch member mounted for common rotation with said feed means chain wheels about the axis of the latter and adapted to engage a carrier member advanced by said lifting chains, the circumferential length of said chain wheels being equal to the distance between the lifting cams of said lifting chains and the angular position of said catch member with respect to said chain wheels being so selected that each subsequent lifted carrier member on reaching the chain wheels is engaged by said catch member to be advanced through the semi-circular lead-in track portion to the leading track portion.

5. The machine according to claim 3 in which said carrier return means comprises for each carrier group at least one lead-off wheel mounted for rotation about the axis the carrier retun means chain wheels and having a resilient surface and a suflicient diameter to cause the carrier members upon reaching the lower end of the leading track portion to be resiliently engaged by the surface of said leadoif wheels, said lead-off wheels being arranged adjacent said return chain wheel for rotation independently of the latter.

6. The machine as claimed in claim 5 further comprising a brake device acting on said lead-off wheels for braking their free rotation.

7. The machine as claimed in claim 1 further comprising driving means for said carrier feed means, said carrier return means, and said carrier driving means, control means fo said driving means allowing the continuous adjustment of the speed thereof, a feed cylinder mounted for rotation above said guide tracks for feeding a web of material to be treated to the carrier members moving through said tracks, a tensioning roller for said web mounted for rotation on a horizontally extending roller shaft, vertically extending guide means engaging the ends of said roller shaft and allowing a free vertical up and down movement of the latter, means coupling said roller shaft to said control means to adjust the latter in response to the vertical position of said roller shaft, whereby the web to be treated can be passed from a source of web supply underneath said tensioning roller towards and over said feed cylinder and consequently variations in the tension of said web cause a vertical displacement of said tensioning roller and an adjustment of said control means tending to counteract said variations.

8. The machine as claimed in claim 1, further comprising a feed cylinder mounted for rotation above said guide tracks for feeding a web to be treated downwardly to the carrier members moving throuhg said tracks, a guide roller, lever means extending across said feed cylinder pivotally mounted at one end and carrying said guide roller at its opposite end, a pressure roller carried by said lever means and resting on said feed cylinder, and support means adapted to receive a supply roll of a web of sheet material, whereby said web from said supply roll may be passed over said guide roll and between said pressure roll and feed cylinder.

9. The machine as claimed in claim 8 comprising two of said supply roll support means, one on each side of the machine, and two feed cylinders arranged side by side for feeding the web coming from a web supply roll placed on the support means on the one or the other side of the machine, respectively, means coupling said feed cylinders with the machine driving means for driving said cylinders in synchronism with said carrier driving means, said coupling means including an electrically controlled clutch and brake mechanism adapted to alternately couple one feed cylinder to said driving means while holding the other feed cylinder stationary, and vice versa, a first web sensing means arranged to sense a web passing from a supply roll placed in the supports on the one side of the machine to the associated feed cylinder, and a second web sensing means arranged to sense a web passing from a supply roll arranged on the support means on the other side of the machine to the feed cylinder associated therewith, said two web sending means so controlling said clutch and brake mechanism that when a web supply roll on the one side of the machine has run out the associated feed cylinder feeding said web is braked to a stop and the other, stationary feed cylinder is started for feeding the web of a full web supply roll placed on the supports on the other side of the machine.

References Cited UNITED STATES PATENTS 3,151,354 10/1964 Boggs 226173X 3,300,365 1 1967 Roos 83326 X RICHARD A. SCHACHER, Primary Examiner US. Cl. X.R. 226-173 

